Was I Scammed

I have had low broadband speeds all day, and after several hours of dealing with PlusNet customer services and getting nowhere, I feel that I was pushed down the road of having to get an engineer out to look at the problem. On a number of occasions PlusNet were all too forward about telling me that it would cost me £50 if the engineer could not find a fault. After booking an engineer to call out tomorrow and agreeing to pay a call out fee if a fault could not be found, suddenly my broadband speed was back to its normal speed again. Would PlusNet have deliberately lowered the speed all day to force me to get an engineer out, somehow the whole thing feels a bit strange and I feel like I was scammed.